Mechanisms of antiviral immunity and tolerance in the intestinal epithelium of Jamaican Fruit Bats

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Summary The gastrointestinal (GI) tract is a major target organ for viral infection in bats, but infections rarely cause typical symptoms of viral enteritis such as diarrhea. The long-term goal of our project is to understand the specific innate immune response mechanisms of the intestinal epithelium that enable bats to sustain viral infection without experiencing cytopathic effects and intestinal barrier dysfunction. We hypothesize that protective type I and type III interferon (IFN) responses in Jamaican Fruit Bats (Artibeus jamaicensis, JFBs) enable persistent, asymptomatic viral infection of the gastrointestinal epithelium. To test our hypothesis, we will utilize a novel in vitro model of the JFB intestine, 3-D enteroids, which are complex long-term cultures of primary intestinal epithelial cells generated from adult tissue-derived stem cells. Responses in the gut epithelium of JFBs will be compared to those induced in human enteroids. In Aim 1, we will define type I/III IFN responses of JFB enteroids to viral infection. In Aim 2, we will determine to what extent type I/III IFNs impact viral replication and barrier function in the gastrointestinal epithelium of JFBs. We will analyze intestinal epithelial cell responses to three single-stranded RNA viruses that can infect JFB cells: H18N11 influenza virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and Cedar virus, a non-pathogenic henipavirus. Specifically, we will analyze the kinetics of viral replication and type I/III IFN activation in the enteroids and will also perform a comprehensive proteomics analysis of virus-infected intestinal epithelial cells. To assess the role of virus-induced type I/III IFNs for gastrointestinal epithelial pathology, IFN signaling will be induced or inhibited, and the impact on enteroid susceptibility to viral infection will be analyzed. We also will measure epithelial cell viability, barrier and repair functions that are commonly disrupted during viral enteritis. Our project is technologically innovative, because we will, for the first time, analyze viral infection in enteroid cultures derived from JFBs and because we also will perform a complete proteome analysis of the JFB intestinal epithelium. The proposed work is conceptually innovative, because it will define how virus-induced type I/III IFNs impact intestinal epithelial function and integrity. Our proposed work is significant, because it will provide novel insights in the epithelial cell-intrinsic innate immune mechanisms involved in asymptomatic infection of the bat intestine with viral pathogens, which has important implications for potential pathogen spillover events.